A spokeswoman said on Sunday that one of the patients was receiving care in Sydney, while the other two were in a stable condition in Canberra.

"People are reminded not to pick and eat any wild mushrooms as it can be extremely difficult to distinguish Death Cap mushrooms from other edible mushrooms," ACT Chief Health Officer Dr Paul Kelly said in a statement.

He asked for the patients' privacy to be respected and said there were no further update in the case.

ACT Health has advised people displaying symptoms of stomach aches, nausea, vomiting and diarrhoea and who purchased and ate mushrooms from Woolworths in Dickson on or around the same date to seek immediate medical attention.

Names and other details of the victims have been withheld, including their ages and gender.

All three live in the same household and presented to Calvary Hospital over a 48-hour period with similar symptoms.

On Sunday, a Woolworths spokesperson confirmed the company was working with ACT Health but said no other incidents had been reported.

Just one death cap mushroom contains enough poison to kill an adult.

Symptoms of death cap mushroom poisoning include stomach aches, nausea, vomiting and diarrhoea, and generally appear six to 24 hours after ingesting the mushrooms.

There have been four fatalities and 12 reported incidents of poisoning associated with death cap mushrooms in the ACT.